Juvenile hormone (JH) is known to have a number of functions in the control of development and reproduction in insects, but little is known regarding the mechanism by which JH affects specific cells. At present, it is speculated that JH functions through intracellular receptors to alter gene expression, as has been demonstrated for the steroid hormones. However, the data available are not conclusive. The mechanism is of interest from the basis of understanding whether the steroid mechanism is ubiquitous for all lipid regulatory molecules, but a more practical aspect is the potential for control of insect growth and reproduction by interrupting the action of JH. Analogs of JH are used in the control of flood water mosquitos since the cessation of use of DDT. Effective disruption of the life cycle of these insects has a direct impact on the control of vector born diseases. Furthermore, JH analogs have also been used to control parasitic flies of cattle by inclusion in their food. Additional analogs have been put to agricultural use. Preliminary research has indicated that binding proteins for JH can be detected in the cytosol of fat body, a tissue that responds to the hormone. The proposed research will necessitate modification of the techniques used for the locust so that the grasshopper can be used as a model system. The major objectives are to determine whether the cytosol binding protein is truly a receptor, and to confirm that hemolymph and cytosol binding proteins are not intra- and extra-cellular forms of the same molecule. Analsyses will be directed toward determining whether the cytosol receptor complexed with JH is transported into the nuclei of the target tissue where it can interact with chromatin. The methodology will involve protein purification by column chromatography, characterization by electrophoresis, immunological techniques, and ultracentrifugation, nuclear isolation, detection of hormone binding, photoaffinity labelling, short term tissue culture, and thin layer chromatography to monitor metabolism.